The purpose of this study was to survey the weight status of children and adolescents with autism spectrum disorders (ASDs) in Iranian pupils and further to investigate the most likely associated factors such as demographics, autism severity and medications. The survey was designed to provide a random sample of 113 children and adolescents (boys = 90, girls = 23) aged 7-14 years old attending autism-specific schools in Tehran in 2010. The findings revealed that 50.4% of these young children were in the limits of normal weight, but 8.7% were underweight, 13.3% were overweight, 11.5% were obese, and 15.9% were severely obese. There were significant associations between obesity and poverty level, age, sex and socioeconomic state. We conclude that with increase in the prevalence of ASD, there was found a growing rate of obesity in these children. (Contains 3 tables and 1 figure.)